1. Field of the Invention
The present invention relates to a precise polishing apparatus and a precise polishing method for polishing a substrate such as a wafer with high accuracy.
2. Related Background Art
Recently, fine arrangement and multi-layer wiring of semi-conductor devices have been progressed and, thus, there has been requested to provide precise polishing apparatuses for flattening a surface of a substrate such as a semi-conductor wafer made of Si, GaAs, InP or SOI with high accuracy. Among them, as a precise polishing apparatus for accurately flattening the surface of the substrate such as a wafer on which semi-conductor elements are formed, a chemical mechanical polishing (CMP) apparatus is known.
Conventional CMP apparatuses can be divided into two types shown in FIGS. 10 and 11.
(1) FIG. 10 is a schematic view of a polishing work portion of the CMP apparatus in which the polishing (abrasion) is effected with a polished surface of a wafer 100 facing downwardly.
As shown in FIG. 10, the wafer 100 is held with the polished surface (surface to be polished) thereof facing downwardly, and the wafer 100 is polished by urging the wafer against a polishing pad 502 having a diameter larger than that of the wafer while rotating the wafer. During the polishing, abrasive agent (slurry) is supplied onto the polishing pad 502.
In the apparatus of this kind, as methods for holding the wafer onto a wafer chuck 501, vacuum suction or adhesion by using wax, solution or pure water has been adopted and, in some cases, a guide ring (not shown) is provided on a periphery of the wafer 100 to prevent deviation of the wafer 100. The diameter of the polishing pad 502 on a polishing table 506 is greater than that of the wafer 100 by 3 to 5 times, and suspension obtained by mixing fine powder of silicon oxide with solution of potassium hydroxide is used as the slurry.
(2) On the other hand, as shown in FIG. 11, there has been proposed a technique in which a wafer 100 is held on a wafer chuck 901 having a guide ring (not shown) and disposed on a wafer table 906 with a polished surface thereof facing upwardly and the wafer 100 is polished by using a polishing pad 802 having a diameter smaller than that of the wafer 100.
In such polishing apparatus and method, the substrate such as the present semi-conductor wafer having a diameter of eight inches can be polished exclusively. However, recently, since fine arrangement of semi-conductor integrated circuits and large diameter wafers have been proposed, it is guessed that the wafer having 8-inch diameter will be replaced by a wafer having 12-inch diameter in the near future.
In order to polish the large diameter wafer, there arise the following problems in the conventional techniques.
In the conventional polishing apparatuses, although the polishing ability is adjusted by making a thickness and elasticity of the polishing pad optimum to polish the 8-inch wafer, in this case, it is difficult to ensure fine adjustment and uniformity of material of the polishing pad and, thus, it is very difficult to polish the large diameter wafer such as 12-inch wafer with high accuracy.
For example, in the conventional polishing methods, it is difficult to obtain a uniform polished amount through the entire surface of the wafer by using the polishing pad having the diameter smaller than that of the wafer. Further, if the entire polished surface of the wafer is polished by the polishing pad having the diameter smaller than that of the wafer, the polishing time will be increased considerably. Further, if the wafer is polished at once by using the polishing pad having the diameter greater than that of the wafer by twice or more, the polished amount near an outer periphery of the polishing pad will become greater than the polished amount near a rotational center of the polishing pad due to difference in peripheral speed between the rotational center of the polishing pad and the outer periphery of the polishing pad.
In addition, the polishing pad may be abraded or deformed into a donut shape since a part of the polishing pad is only in contact with the wafer. The polishing pad is applied with a pressure when it polishes the wafer and the polishing pad may be deformed due to the pressure. Such matters may affect the uniformness and the flatness of the polished surface.
Further, as is in the conventional cases, when the wafer with the polished surface thereof facing downwardly is polished by opposing the polishing pad having the diameter greater than that of the wafer by twice or more to the wafer, the abrasive agent is continued to be supplied to not only an area of the polishing pad with which the wafer is contacted but also the entire area of the polishing pad. As a result, a large amount of abrasive agent is consumed, thereby making the polishing expensive.
An object of the present invention is to eliminate the above-mentioned conventional drawbacks.
To achieve the above object, according to the present invention, there is provided a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing is effected in conditions that a rotation axis of the polished body is deviated from a rotation axis of the polishing pad and that the polishing pad is contacted with an entire area of the polished surface of the polished body.
The present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polished body holding means includes a drive means for oscillating the polished body in directions along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing head includes a drive means for oscillating the polished body in directions along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing is effected in conditions that a rotation axis of the polished body is deviated from a rotation axis of the polishing pad and that the polishing pad is contacted with an entire area of the polished surface of the polished body.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polished body is oscillated along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing pad is oscillated along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating and revolving the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing is effected in conditions that a rotation axis of the polished body is deviated from a rotation axis of the polishing pad and that the polishing pad is contacted with an entire area of the polished surface of the polished body.
The present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating and revolving the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polished body holding means includes a drive means for oscillating the polished body in directions along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating and revolving the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing head includes a drive means for oscillating the polished body in directions along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating and revolving the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing is effected in conditions that a rotation axis of the polished body is deviated from a rotation axis of the polishing pad and that the polishing pad is contacted with an entire area of the polished surface of the polished body.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating and revolving the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polished body is oscillated along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly and for rotating and revolving the polishing pad around a center of the polishing surface, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing pad is oscillated along the polished surface, and a sum of a maximum value of a distance between the center of the polished surface and the center of the polishing surface of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention can uniformly polish the polished body by providing the above-mentioned polishing apparatus or method.
In the precise polishing apparatus, the polished body may comprise a semi-conductor wafer.
In the precise polishing apparatus, the polished body holding means may include an equalizing mechanism for urging the polished body against the polishing pad with uniform pressure. As a result, polishing unevenness due to uneven pressurization can be prevented.
In the precise polishing apparatus, a ratio between the number of rotations of the polished body and the number of rotations of the polishing pad may be selected within a range of 1:0.5 to 1.5.
In the precise polishing apparatus, the number of rotations of the polished body and the number of rotations of the polishing pad may be equal.
In the precise polishing apparatus, the diameter of the polishing pad may be smaller than twice of the diameter of the polished body.
In the precise polishing apparatus, the oscillation may be a reciprocal linear movement.
In the precise polishing apparatus, the oscillation may be a reciprocal arc movement. As a result, unevenness in a peripheral speed of oscillation sliding, thereby polishing the polished body uniformly.
Further, the present invention can uniformly polish the polished body by providing the following polishing apparatus or method.
That is to say, the present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating and revolving the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing is effected in conditions that a rotation axis of the polished body is deviated from an axis of the polishing pad and that the polishing pad is contacted with an entire area of the polished surface of the polished body.
The present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating and revolving the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polished body holding means includes a drive means for oscillating the polished body in directions along the polished surface, and a sum of a maximum value of a distance between the center of the polished body and the center of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating and revolving the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing head includes a drive means for oscillating the polished body in directions along the polished surface, and a sum of a maximum value of a distance between the center of the polished body and the center of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating and revolving the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing is effected in conditions that a rotation axis of the polished body is deviated from an axis of the polishing pad and that the polishing pad is contacted with an entire area of the polished surface of the polished body.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating and revolving the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polished body is oscillated along the polished surface, and a sum of a maximum value of a distance between the center of the polished body and the center of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
The present invention further provides a precise polishing method using a precise polishing apparatus comprising polished body holding means for holding a polished body with a polished surface thereof facing upwardly and for rotating and revolving the polished body around a center of the polished surface, a polishing head for holding a polishing pad having a diameter greater than a diameter of the polished body with a polishing surface thereof facing downwardly, and a supply opening provided in the polishing head and adapted to supply abrasive agent to the polished surface via the polishing pad, and wherein the polishing pad is oscillated along the polished surface, and a sum of a maximum value of a distance between the center of the polished body and the center of the polishing pad generated due to the oscillation and a radius of the polished body is selected to become smaller than a radius of the polishing pad.
In the precise polishing apparatus, the polished body may comprise a semi-conductor wafer.
In the precise polishing apparatus, the polished body holding means may include an equalizing mechanism for urging the polished body against the polishing pad with uniform pressure.
In the precise polishing apparatus, a drive means for rotating the polishing pad is provided, and a ratio between the number of rotations of the polished body and the number of rotations of the polishing pad may be selected within a range of 1:0.5 to 1.5.
In the precise polishing apparatus, a drive means for rotating the polishing pad is provided, and the number of rotations of the polished body and the number of rotations of the polishing pad may be equal.
In the precise polishing apparatus, the diameter of the polishing pad may be smaller than twice of the diameter of the polished body.
In the precise polishing apparatus, the oscillation may be a reciprocal linear movement.
In the precise polishing apparatus, the oscillation may be a reciprocal arc movement.
In the precise polishing apparatus, there may be provided a distance measuring means for measuring a distance between the polishing pad and the polished body which are opposed to each other. With this arrangement, the rotating polished body can be prevented from escaping.
In the precise polishing apparatus, there may be provided a drive means for rotating the polishing head in a direction opposite to the rotational direction of the polishing head.
In the precise polishing apparatus, a sum of a distance between the center of the polishing pad and the center of the polished body and a radius of the polished body may be selected to become smaller than a radius of the polishing pad. With this arrangement, the polished body can be polished uniformly.
In the precise polishing apparatus, the supply opening may be positioned at an end of a slurry supply passage passing through the rotational axis of the polishing head.
In the precise polishing apparatus, there may be provided a rotary joint for connecting a first slurry supply tube disposed in the slurry supply passage with a second slurry supply tube connected to a slurry supply tank.
In the precise polishing apparatus, the slurry supply passage passing through the rotational axis of the polishing head may extend through a revolution body for revolving the polishing head. With this arrangement, the slurry can be supplied stable for a long time.
In the precise polishing apparatus, a diameter of the polished body holding means may be greater than the diameter of the polishing pad.
In the precise polishing apparatus, the polished body holding means may hold the polished body in such a manner that the center of the polished body is deviated from a center of the polished body holding means.
In the precise polishing apparatus, a sum of a maximum distance between the center of the polishing pad and the center of said polished body holding means and a radius of the polishing pad is selected to become smaller than a radius of guide ring which is a part of said polished body holding means. With this arrangement, a thickness of the polishing pad can be maintained uniformly during the polishing.
In the precise polishing method, the rotational direction and the revolving direction of the rotating and revolving polishing pad may be opposite to each other. With this arrangement, the polished body can be polished uniformly.
In the precise polishing method, the polishing pad may be disposed above and opposed to the rotating polished body with a gap having a value of a half of the thickness of the polished body, and the polishing pad may be contacted with the polished body after acceleration of rotation of the polished body is stopped to rotate the polished body at a constant speed. With this arrangement, the rotating polished body can be prevented from escaping.
In the precise polishing method, a sum of a distance between the center of the polishing pad and the center of the polished body and a radius of the polished body may be selected to become smaller than a radius of the polishing pad. With this arrangement, the polished body can be polished uniformly.
In the precise polishing method, the entire surface of the polishing pad may be urged against the polishing body holding means holding the polished body to polish the polished body by the polishing pad.
In the precise polishing method, the polished body holding means may hold the polished body in such a manner that the center of the polished body is deviated from a center of the polished body holding means.
In the precise polishing method, a maximum sum of a distance between the center of the polishing pad and the center of said holding means and a radius of the polishing pad is selected to become smaller than a radius of guide ring which is a part of said polished body holding means. With this arrangement, a thickness of the polishing pad can be maintained uniformly during the polishing and the polished body can be polished uniformly.
A further object of the present invention is to provide a precise polishing method in which a direction of rotation of said polishing pad is opposite to a direction of revolution of said polishing pad.